Editing Crop rotation (section)

=== Green manure ===

[[Green manure]] is a crop that is mixed into the soil. Both nitrogen-fixing legumes and nutrient scavengers, like grasses, can be used as green manure.<ref name="lamb2010">{{Cite report |last1=Lamb |first1=John |last2=Sheaffer |first2=Craig |last3=Moncada |first3=Kristine |date= 2010 |chapter=Chapter 4 Soil Fertility |title=Risk Management Guide for Organic Producers |publisher=[[University of Minnesota]] }}</ref> Green manure of legumes is an excellent source of nitrogen, especially for organic systems, however, legume biomass does not contribute to lasting [[soil organic matter]] like grasses do.<ref name=lamb2010/>